Telegraph repeater system



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March 22, 1932.

Patented Mar. 22, 1932 UNITED STATES GILBERT SANFORD "VERNAM,

OF RIVER EDGE, NEW JERSEY, lASSICrNOR ,TO

TELEGRAPH REPEATER SYSTEM 'a `Application, filed November 3Q, 19x29. Serial No. 410,711. n

y This invention relates to telegraph systems .and more particularly to a repeater for single line telegraph systems. y p

former single line repeater systems it v has been the practice to utilize non-polar relays or combinations of polarized` relays. Neutral relays whichdepend on strength of vcurrent for their operation have been found to be too sluggish in their action to be satisfactory for automatic printer systems. Heretofore, the polar type of single line repeater required ya minimumjof fourv or more relays and a J'correspondingly complicated' hook-up. Accordingly, this invention has for its object to provide a simple,eliicient and less expensive polar single line repeater employing but two standard, polar relays in its operation.

In carrying out this invention there is provided at the repeater station a pairof differentially'wound polar relays having three sepl arate windings. Two windings of each relay are differentially connected', the second terminalof one coil being connected to ground through an impedance and resistance, the other side of the second coil in each case beingr connected to the outgoing line. The third coil of each relay is energized by a small current from a local battery of Suchdirection that it always tendsrto move the tongues of the relays to their right hand or marking contacts. y 1

The apex of the differentially connected coils of one relay is connected to the tongue of the other relay in each case. The tongues of both relays, when the line is closed, rest on their right hand or -marking contacts which are connected to one pole of a source of potential; the other polebeing grounded. The repeater operates as follows: n

Referringto the drawings; A andL B 1ndicate the terminals of the telegraph line. The line is divided into twoy sections 1 and 2 by a repeater station R. There are two polar relays 3 and 4 at R, each having a plurality of windings. Windings 5 and 6 of relay 3 are connected differentially at 7 and likewise windings 8 and 9 of relay 4 are connected differentially at 10. .The other terminal of coil 5 of relay 3 is connected to groundat 13 through impedance 11 and resistance 12.

4nected in the same tact 19 of relay 3 Likewise the corresponding terminal of coil 8 of relay 4 is connected to ground at 16 through impedance 14 and resistance 15. The incoming linel from station A is joined to the second terminal of coil 6. Line 2 is contheir apex 7. Tongue 18 of relay 3 is connected to the coils 8 and 9 of relay 4 at 10. Conis connected through resistance 2O to a source of potential 21 which is grounded at 22. Contact 23 of relay 4 is connected through a resistance 24 to a source: of potential 25 which is grounded at 26. Each relay has a coil 27 which is constantly ener-l gized from a battery 28 through a resistance 29. There is only a light current flowing through the coils 27 and its direction is such that it fconstantly tends to move the tongues 17 and 18 over totheir marking contacts -19 and 23. At station A, 34 indicates an ordinary Morsekey and 36 a relay. vAt station B, 35 and 37 indicate similar apparatus, though of course it is understood that suitable automatic printer apparatus might be` substituted.

In the invention in its preferred form windings 5 and 6 of relay'3 and windings 8 and 9 of relay 4 each have a resistance of 85 ohms.` Windings 27 of relays 3 and 4 eachk have a resistance of 300 ohms.l The constants of the circuit are so arranged that with the keys 34 and 35 closed, current of vabout .060 ampere Hows in coil 6 of relay 3 and in coil 9 of relay 4. Approximately .O35 ampere flows through coil 5 of' relay 3 and coil 8`of relay 4. About .025 ampere flows through the coils 27 of relays 3 and 4 but these coils have fewer turns than the other coils and this current is about equivalent in its effect to .O05 ampere in the coil similar to the others just referred to. Since coilsV 6 and 27 of re lay 3 aid each other and their pull is opposite to coil 5, the net result is equivalent to a current of .O30 ampere in a single coil acting in the same direction as coil 6. When no current flows through coil 6, then coil 5 will move the relay tongue to the opposite contact owing to its pull of .035 ampere overcoming the constant marking pull of '.005 ampere of manner to coil 9. Tongue' 5 '17 of relay 4 is connected t-ol coils 5 and 6 at station A to ground..

in asimilar manner las:

lcuit is restored from. point 7 coil 27. Relay 4 is operated in the same manner.

With the keys at both stations closed and considering the circuit from station A, the current flows. from positive battery 25 through resistance 24, contact and 'tongue 17 of relay 4 to the junction 7 ofV coils 5 and 6 ot relay 3 where part of the current goes through the coil; -,theimpedance coil 11 and resistance 12.130. ground at 13. Thelarger part of the current in battery 25, however, goes through coil 6, the relay 36, andthe key 34 at The armature of relay 3 is held to its marking contact 19 due to the pull et coil 6 which is stronger than that `trom coil 5- whieh tends to` move the armature in the` opposite direction.. On opening the key atstation A the circuitvwill be opened through coil' 6 only, andi the tongue ot relay 3I will' bei pulled to its spacing contact 30 whil'ethe rel-ay. 36 at stationA is also released. The armature of relay 4. will remaink against its marking contact. 23 when the circuits through coils 8" andy 9 are both` opened at contact 19 of relay 3,.because of. the tendency oi coil 27 of relay 4toholdt-ongue 17 on contact 23. `When' the circuit through coil 9 is operiert the relay atstationBliS also released, that is,.0pening the key at station A releases the armatures otV the relays at stations A andB.

Upon. closing thezkey at station A, the cir 0lrelay 3 through coil. through. the relay and: key7V of station A toground, thusoperating the relay at that station and. also moving the tongue of relay 3 backtocontact 19.4 then tongue118 makeswithcontact 19the circuit. through coil 9 of relay 4- willbe restoredand. relay 37 at station B will be operated; A signal. from stationBwould be repeated through. relay 4 from. station A toy B, except that relay 4 would. operate instead of relay If the key 35 at station B. were opened while the key at stationA. was open,

no effect wouldA be noticed` at` station A be i cause line` 2. isalready open at the tongue 18 and the contact19 of relay 3, and1 relay 4 is held to its marking contact 23. by. the current in coil27 asexplained above. Iii the key at stationA is subsequently closed and thekey at station B remainsopemthe relay SavillA go back to its marking contact. 19 and'` relay 4 will be operatedby the current through its winding 8 to repeat the break signal. toistation A. StationA then cannot send because line- 1 is` openiat the tongue 17 andthe contact 23 of relay. 4.

lnductances 11 and; 14 are placed respectively in series with coil 5 of'relay 3,..and coil 8 of relay 4, and.

tance of the distant relay, so that when the circuit through the differentially linev relays, each. responsive grounded. resistances. 1Q and 15 1n order to compensate for the indue-a connected coils of one relay is closedl by the tongue of the other relay going to marking, the current in the coil 5 or 8 of whichever relay happens to be energized will not build up fasten than the coil with which it is differentially associated and thus pull that relay to spacing.

W'hat isclaimed is 1. In a single line repeater a pair of relays, each relay being provided with three windings and two-ot which are adapted to exert a pullin one direction and the third in the opposite direction.

2: A! telegraph repeater comprising a pair of polar relays each having a continuously energized' biasing winding and a pair of differential windings said differential windings being in unbalanced circuits.

3. A telegraph repeater comprising a pail` of polar relays,..each havinga continuously energized.. winding anda pair of' differential windings,` said differential windings being in unbalanced circuits, and said continuously energized. windingbeing. adapted to aid one oil'i` said differential' windings and' to oppose' the i other of said` windings.

4.` A telegraph repeater comprising a pairV of' line rel`ays,.each. of said! relays having a` continuously energized' winding and a pair of differential windingasaid differential. windingsbeing in unbalanced circuits, one terminal. offone4 of. said. differential. windings being connected to. the associated' line section, the= other. terminal. off said winding and alterminal of.' the, other. differential winding being connected to a Contact' ofthe other line relay.

6... A telegraphlrepeater comprising a pair ofli'ne relays, continuously energized winding and a pair of" differential windings,v said differential windings being. inr unbalanced circuits, and one of said differential windings being alone opened on open line input signals.

7 L ln a signalling system, a telegraph line divided into sections, and means comprising a single source of asingle potential; and; a single polar relay associated' with each' section for repeating4 signals from. one into anotherv of saidv sections.

8.v A telegraph-system comprising a pair of toV input signals and irresponsive to output signals, said relay eachhaving a continuously energized winding andJ a pair of differential windings, said differential windingsbeing in unbalanced circuits, and means responsive tothe operation of" one of said line relays for'rendering'the other line relay irresponsive byopening both and each of said relays having athe diferentialwindings of said relay when the responsive line` relay operates in one'direction and by closingboth the differential windings of said relay when the responsive.A

line relay operates in the other direction.

9. A telegraph repeater having a pair off polar relays each possessing a pair of normal- 

